Radio cartridge with automatic tuning device for use with magnetic tape cartridge player

ABSTRACT

A radio cartridge with a radio receiving circuit for use with a player unit for an endless magnetic tape cartridge. The radio cartridge includes a lever rotatably mounted within a casing, and a pinch roller rotatably mounted on the lever. The pinch roller is moved by the swingable lever to abut against a capstan which is provided within the player unit, and is rotated by the capstan. Rotation of the pinch roller is imparted to an operating shaft of a tuning element in the radio receiving circuit to vary the radio receiving frequency. The lever is swung in such a direction to move the pinch roller away from the capstan when the radio is tuned to the radio wave so that rotation of the operating shaft is terminated and the radio is automatically tuned.

United States Patent 1 3,612,776

[72] Inventor ltsukiBan 2,081,752 5/193 7 Linsell 179/100.11

829, Higashi-Oizumimachi, Nerima-ku, 3,536,859 10/1970 Tolar 179/ 100.1 1 Tokyo-Japan OTHER REFERENCES [21] App]. No. 797 092 [22] Filed 6, 1969 Billboard, 22 Apr. 1967, pp. 70.- 71.

[45] Patented Oct. 12, 1971 Primary Examiner-Bemard Konick Assistant Examiner-Raymond F. Cardillo, Jr.

Attorney-Jacobs & Jacobs [54] RADIO CARTRIDGE WITH AUTOMATIC TUNING DEVICE FOR USE WITH MAGNETIC TAPE fi ABSTRACT: A radio cartridge with a radio receiving circuit for use with a player unit for an endless magnetic tape car- [52] L8. tridgg; The radio cartridge includes a lever rotatably mounted 2 within a casing, and a pinch roller rotatably mounted on the [51] lnt.Cl ..Gl1b 31/00,

in lever. The pinch roller is moved by the swingable lever to abut H against a capstan which is provided within the player unit, and

Fleld of Search is rotated the capsmr Rotation of the pinch roller is im- 325/471 parted to an operating shaft of a tuning element in the radio receiving circuit to vary the radio receiving frequency. The

[56] References cued lever is swung in such a direction to move the pinch roller UNITED STATES ENTS away from the capstan when the radio is tuned to the radio 2,662,975 12/1953 Schwartz 179/ 100.11 X wave so that rotation of the operating shaft is terminated and 2,880,31 1 3/1959 Bray 325/471 the radio is automatically tuned.

PATENTEUUEI 12 l97| SHEET 1 [IF 4 INVENT OR PATENTED [1U 12 l97| SHEET 2 OF 4 RE EWIIG Cl ROUIT INVENT OR ATTORNEY PATENTEUUCT 12 197i sum 3 OF 4 3.612.776

I v INVENTOR ATTORNEY RADIO CARTRIDGE WITH AUTOMATIC TUNING DEVICE FOR USE WITH MAGNETIC TAPE CARTRIDGE PLAYER BACKGROUND OF THE INVENTION The present invention relates to a radio cartridge with a radio receiving circuit which enables one to listen to the radio by utilizing a magnetic tape cartridge player unit, and more particularly to a radio cartridge capable of automatic tuning. A radio cartridge of such a class has been commercially available, which includes a radio receiving circuit and which is adapted to be convertible for an endless magnetic tape cartridge for reproducing recorded information by means of the player unit which is so called car stereo, home stereo." The radio cartridge of this class is actuated by inserting the same in the tape player unit, as in the same manner as the endless magnetic tape cartridge, to allow it to receive the electrowaves such as AM (amplitude modulation), or FM (frequency modulation). Such a radio cartridge must, of course, have tuning elements such as a variable condenser, variable inductance coil or the like to rotate an operating shaft of the tuning element to thereby tune to the frequency of the desired radio broadcast wave. Since the radio cartridge of the class as described is adapted to convertibility for the endless magnetic tape cartridge, it provides a small front portion which is exposed when inserted into the player unit. On the other hand, a tuning dial for rotatably operating the operating shaft for the tuning element and a station-indicator dial must be provided in this limited exposed portion. This causes the size and configuration of the dial to be reduced and its operation to be difficult, particularly when the driver of the car is trying to concentrate on driving. The tuning element should preferably be for automatic tuning, but it is difficult to employ a pushbutton switch for automatic tuning in a radio cartridge since five to pushbuttons are required to this end.

SUMMARY OF THE INVENTION It is therefore a primary object of the invention is to provide a radio cartridge with a radio receiving circuit which is adapted to be inserted into a player unit for an endless magnetic tape cartridge.

A further object of the invention is to provide a radio cartridge wherein an operating shaft for a tuning element for the radio receiving circuit is rotated by the rotating force of a capstan in the player unit.

Another object of the invention is to provide a radio cartridge wherein a pinch roller is rotatably mounted on a rotatable lever, said pinch roller being rotated by abutting against the capstan to rotate a tuning element operating shaft.

Still another object of the invention is to provide a cartridge wherein the tuning element operating shaft is caused to initiate its rotation and continue the same by actuating means for swinging a lever from a first to second position to abut the pinch roller against the capstan, an electromagnet for maintaining the lever in said second position, and the electromagnet is caused to release the lever from its engagement by an electric signal produced in response to the tuning of the radio receiving circuit to return the lever to said first position while the tuning element is maintained in a position to receive the desired radio broadcast wave.

A still further object of the invention is to provide a radio cartridge capable of manual operation of the tuning element by allowing a portion of a drum which is mounted on the tuning element operating shaft to project from the cartridge casmg.

According to the present invention, a radio cartridge is provided so that the pinch roller is away from the capstan when the tuning element is in the receiving position for the desired radio broadcast wave to fully disconnect the operating shaft from the rotating power source whereby no slight aberration of tuning is caused by motor inertia as in the case of conventional tuning means.

These and other objects and advantages of the invention will be apparent from the following description and accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a'plan view of a radio cartridge embodying the invention with a portion in transverse section;

FIG. 2 is an enlarged perspective view of the drum shown in FIG. 1;

FIGS. 3a and 3(b) are sectional plan views showing the detailed construction of the electromagnet of FIG. 1 and relationship between a magnetic substance plate and the electromagnet;

FIG. 4 is a circuit diagram for the radio cartridge and the player unit shown in FIG. 1;

FIGS. 5 and 6 are plan views of another forms of the radio cartridge according to the present invention with a portion in transverse section;

FIG. 7 is an enlarged perspective view of the rotatable lever shown in FIG. 6;

FIG. 8 is a circuit diagram for the purpose of illustrating the operation of the switch shown in FIG. 6;

FIG. 9 is a plan view of another modified form of the radio cartridge inserted in the player unit with a portion in transverse section;

FIGS. 10(a) and 10(1)) show electrical circuits different to each other which are for the electromagnet shown in FIG. 9;

FIG. 11 is an enlarged perspective view of the two levers of FIG. 9 with a portion being omitted away;

FIG. 12 is a plan view of the radio cartridge shown in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, numeral 20 indicates a radio cartridge casing which comprises a bottom plate 21, top plate 22, front wall 23, rear wall 24, and a pair of sidewalls 25, 26 and is sub stantially similar to a currently available endless magnetic tape cartridge casing in its shape. A lever 27 is pivotally mounted by a shaft 28 on the bottom plate 21 within the interior of the casing 20. One end 27 of lever 27 is connected through a spring 29 to a pin 30 projecting from the bottom plate 21 so as to be urged counterclockwise and the other end 27, passes through a window 25, in the sidewall 25 outwardly of the casing 20. A pinch roller 31 is secured to a rotatable shaft 32 rotatably pivoted to the lever 27. The pinch roller 31 has the same structure as that of a pinch roller stored in a conventional endless magnetic tape cartridge and it passes from a window 23, formed in the front wall 23 outwardly of the casing 20. A belt 33 extends around a rotatable shaft 32 and a drum 34. Positioned within the drum 34 is a tuning element 35 such as a variable condenser which is mounted on the bottom plate 21. The drum 34 is in turn mounted on an operating shaft 36 for rotating the tuning element 35. As best seen from FIG. 2, the drum 34 is provided with a belt groove 37 at the periphery thereof. Tuning dials 38, and 38, are engraved on the upper surface and the periphery of the drum 34, respectively. The top plate 22 of the casing 20 is made of a transparent material so as to enable one to see the tuning dial 38,. A window 24, is provided in the rear wall 24 to allow a portion of the drum 34 to project therefrom. This enables the user to manually operate the drum while seeing through the tuning dial 38,. In the casing 20 there are incorporated a radio amplifier, local oscillator, mixing, intermediate radio amplifier, and a detection circuit which are required to reproduce an audible signal. Contacts 39, 40, 40a, 41 and 42 are insulated in relation to one another and are fixed to the exterior of the sidewall The radio cartridge as referred to in the foregoing is inserted into the player as in the case of a conventional endless magnetic tape cartridge. Numeral 45 denotes a deck which is provided within a container (not shown) of the player unit. Guide pins 46, 47 and a guide roller 48 are provided on the deck 45 to guide the radio cartridge which is inserted into the unit from the direction of arrow C. The guide roller 48 is pivoted to a shaft 48, carried by a free end of a bracket 49 of resilient metal plate of which one end is mounted by a screw 50 on the deck 45. The guide roller 48 is urged in the direction of arrow D by the bias of the resilient bracket 49. When the radio cartridge is fully inserted into the unit, the guide roller 48 is also received in the depression 25 and is brought in a predetermined position on the radio cartridge deck 45, as shown in FIG. I. Insertion of the casing into the unit causes the end 27, of the lever 27 to engage the guide roller 48. On the other hand, the guide roller 48 is moved by the resilient force of the bracket 49 in the direction reversed to that of arrow D and is away from the travel path of the lever 27. A capstan 51, magnetic head 52, endmark sensor 53, and a door switch are provided on the deck for reproducing an endless magnetic tape cartridge. The capstan 51 is mounted on a flywheel 55 and passes through a hole (not shown) formed in the deck 45. The door switch 54 is operated by the front wall 23 of the casing 20 to apply current from the power source to the player unit when the radio cartridge is fully inserted. Contacts 39, 40, 40,, 41', and 42' are insulated in relation to one another and are fixed to the deck 45. These contacts are adapted to contact with the other contacts 39, 40, 40,, 41 and 42, respectively when the casing is brought into a predetermined position. The contact 39' is connected to an antenna (not shown). The contact 40' is connected to the input terminal of an amplifier (not shown). The contact 40,, is connected to the input terminal of an amplifier 76 (FIG. 4) as will be described hereinafter. The contact 41' is connected to the negative pole of a power source (not shown). The contact 42' is connected to the negative pole of the power source. A microswitch 56 is mounted on the deck 45 so as to be opposed to the front wall 23 of the casing 20 when positioned. An actuator 56' for the microswitch is adapted to be operated by the front wall 23. The microswitch is designed to be operated only by the radio cartridge and not the endless magnetic tape cartridge. To this end, the front wall 23 is provided with a raised portion to which the actuator 56' may be opposed. The operation of the microswitch 56 will be detailed hereinafter.

An escape arrangement is provided for disengaging the pinch roller from the capstan. This arrangement comprises a swingable lever 57, and electromagnet 62 for retaining the lever 57 and an electromagnetic plunger 63 for controlling swing movement of the lever 57. The L-shaped lever 57 is rotatably pivoted by a shaft 58 mounted on the deck 45. The lever 57 is positioned to allow the one end 57 thereof to engage the one end 27, of the lever 27 when the casing 20 is fully brought into a predetermined position. A spring 59 is interposed between the lever 57 and a pin 60 on the deck to urge the lever 57 counterclockwise. Swing movement of the lever 57 by the spring 59 is arrested by engagement of lever 57 with a stop pin 61. A magnetic plate 62 is fixed to the other end 57, of the lever 57 and an electromagnet 63 is secured to the deck 45 so as to be opposed to the magnetic plate. The lever 57 is connected at its end 57, to an armature 65 of an electromagnetic plunger 64 by means of a spring 66. The plunger 64 when energized functions to swing the lever 57 against the bias of the spring 59.

FIG. 3(a) shows relationship between the electromagnet 63 and the magnetic plate 62 illustrated in FIG. 1. The magnetic plate 62 is of substantially U-shaped configuration and includes a mild steel plate 62, fixed to the lever 57 at the end 57, thereof and a ferrite magnet 62, which is magnetized and secured to the center of the steel plate 62,. The opposite ends of the steel plate 62, are S poles by action of the ferrite magnet 62,. The electromagnet 63 comprises a combination of a pair of yokes 63,, 63, of substantially U-shaped configuration to form E-shaped configuration thereof, as shown, and an exciting coil 63, wound to the joint portion of the yokes. The open ends of the yokes 63,, 63, are opposed to the opposite ends of the mild steel plate 62, and the ferrite magnet 62,, respectively. With this arrangement, the magnetic plate 62 is magnetically attracted to the electromagnet 63 when the plate 62 is in close proximity of the yokes 63,, 63,. Normally deenergized exciting coil 63, is adapted to be energized at the point of a receiving station, as referred to hereinafter, and thereby the drift of the current applied to the coil is in a manner of erasing the magnetic fiux of the ferrite magnet 62,. Energization of the coil 63,, causes, therefore, the electromagnet 63 to release the magnetic plate 62 from magnetically attractive engagement therewith.

FIG. 3b shows relationship between a modified form of the electromagnet 63 and magnetic plate 62. In this instance, the magnetic plate only includes a mild steel plate 62,, and the electromagnet comprises a yoke 63, and the pair of exciting coils 63,, 63,,. Normally energized exciting coil 63, may generate the magnetic fiux so that the electromagnet and the magnetic plate are magnetically attracted to each other when the steel plate 62, is in close proximity of the yoke 63,. The other exciting coil 63, is normally deenergized as in the aforementioned coil 63, but is energized at the point of a receiving station so that the drift of the current applied to the coil is in a manner of erasing the magnetic fiux of the exciting coil 63,,. Energization of the coil 63, causes, therefore, the yoke 63, to release the mild steel plate 62, from magnetically attractive engagement therewith. These arrangement illustrated in FIGS. 3(a) and (b) may perform the same object.

FIG. 4 shows a circuit arrangement for the apparatus of FIG. 1. Like parts are denoted by like numerals in FIG. I. The radio broadcast wave received by an antenna 70 is applied through the contacts 39', 39 to a receiving station'7 I when the casing is held in a predetermined position of the deck. The receiving station 71 is built into the casing 20 and includes the tuning element 35 of FIGS. 1 and 2. The output signal of the receiving station 71 is applied through the contacts 40, 40' to the input terminal of an audiofrequency amplifier 73 in the player unit. An equalizer amplifier 72 is adapted to receive the output signal from the magnetic head 52. The output terminal of the equalizer amplifier 72 is connected to the input terminal of the audiofrequency amplifier 73. The output signal of the equalizer amplifier 72 is nil unless the endless tape cartridge is used. A speaker 74 is connected to the output side of the audiofrequency amplifier 73. AVC (automatic volume control) voltage of the receiving station 71 is applied through the contacts 40,, 40,, to an amplifier 76. The amplifier 76 is arranged in the circuit to generate the positive pulse signal when the AVC voltage reaches the extreme value. The output pulse of the amplifier 76 is applied to the exciting coil 63, (FIG. 3(a)) of the aforementioned electromagnet 63. The current for actuating the receiving station 71 is supplied through the contacts 42, 42 and 41, 41' from the power source 77. The current for actuating a motor 78 for the capstan 51 (FIG. 1 the equalizer amplifier 72, the audiofrequency amplifier 73, and the amplifier 76 is also supplied through the door switch 54 from the power source 77.

Numeral 79 indicates an electromagnetic plunger which is included in the prior art device in which the recording track on the endless magnetic tape is changed over by vertically moving the magnetic head. The plunger 79 is connected through the microswitch 56 and a pushbutton switch 80 to the power source 77 The microswitch is closed on the side of the plunger 64, as seen from FIG. 4, when the radio cartridge is used, whereas when the endless magnetic tape cartridge is used the microswitch is changed over to the side of the plunger 79. From the foregoing it is apparent that the plunger 64 is connected through the microswitch 56, pushbutton switch 80 to the power source 77 in the use of the radio cartridge. The pushbutton switch 80 serves to change over the v recording track in the use of the endless magnetic tape cartridge or select the channel in the use of the radio cartridge. The endmark sensor 53 comprises a pair of contacts which is short-circuited by the endmark of conductive foil, as well known, on the endless magnetic tape.

The operation of the apparatus in FIGS. 1 to 4 will be detailed hereinafter.

When the radio cartridge is moved in the direction of arrow C to the deck for insertion, the lever 27 engages at the one end 27, thereof the other lever 57 (positioned in the dotted line shown in FIG. 1) at the one end thereof at the final stage of the cartridge movement and the lever 27 is slightly swung against the bias of the spring 29 by the strong resilient force of the spring 59. This causes the casing to be brought into a predetermined position on the deck 45 while the pinch roller 31 is away from the capstan 51. The positioning of the casing 20 on the deck 45 as shown in FIG. 1 brings the contacts 40, 40 41, 42 into contact with the respective contacts 40', 40,, 41, 42' and opens the door switch 54 while the microswitch 56 is changed over to thereby allow whole the circuit to be activated. Now, the pushbutton switch 80 is depressed to apply the pulse current to the electromagnetic plunger 64, the armature 65 is actuated and the lever 57 is clockwise swung by the spring 66 against the resilient force of the spring 59. Further, the lever 57 is swung from the dotted line to the solid line shown in FIG. 1, so that the magnetic plate 62 and the electromagnet 63 are magnetically attracted to each other to arrest further movement of the lever 57. On the other hand, the lever 27 is swung by the bias of the spring 29 to abut the pinch roller 31 against the capstan 51 for rotating the pinch roller 31. Rotation of the pinch roller 31 rotates the shaft 36 of the tuning element 35 through the shaft 32, belt 33, and drum 34 to thereby vary the tuning frequency. With this in mind, when the tuning frequency corresponds to the radio broadcasting wave frequency, AVC voltage of the receiving station 71 reaches the extreme value and the pulse current is applied from the amplifier 76 to the coil 63 (FIG. 3(a)) or 63,, (FIG. 3(b)). As a result, retention of the lever 57 by magnetic attraction of the electromagnet 63 and the magnetic plate 62 is released to return the lever 57 to the position shown by the dotted line of FIG. 1. With return of the lever 57, the lever 27 is also returned to its original position to disengage the pinch roller 31 from the capstan 55 so that the tuning element 35 is maintained in the condition when it has been set to the tuning position of the radio broadcasting wave. It will be readily understood that if another wave is to be received, the pushbutton 80 is again depressed and the tuning element will be automatically set to the tuning position for that wave as in the manner as set forth in the above.

As described hitherto, the radio cartridge is capable of selecting the channel automatically or manually, by way of manual rotation of the drum 34.

FIG. 5 shows a modified embodiment of the present invention, in which like parts are designated by like numerals in FIG. 1. Pivotally mounted on a shaft 128 fixed to a bottom plate 121 of a casing 120 for radio cartridge is a swingable lever 127 to which at the top end 127, a rotatable shaft 132 is pivoted through a pillow block (not shown). A pinch roller 131 is attached to the shaft 132. A spring 129 is interposed between a pin 130 attached to the bottom plate 121 and the lever 127 at the midportion thereof to urge the lever clockwise centering round a shaft 128. A stop pin 181 projects from the bottom plate 121 to arrest swing movement of the lever 127 in a position shown by a dotted line of FIG. 5. Fixed to the other end 127,, of the lever 127 on one side thereof, is a magnetic plate 162 to which an electromagnet 163 is opposed and attached to the bottom plate 121. A pushbutton rod 182 is slidably supported by a guide 183 within the casing 120 and the one end of the rod 182 is opposed to the one end 127, of the lever 127 on one side thereof while the other passes through an opening (not shown) in a rear wall 124. A pushbutton 184 is secured to the other end of the rod 182 projecting from the rear wall 124. A tuning element 135 is provided within the casing 120 as in the case of the radio cartridge in FIG. 1. A drum 134 is fixed to an operating shaft 136 for rotating the tuning element 135. A belt 133 extends between the shaft 132 and the drum 134. Mounted on the sidewall 126 are contacts 139, 140, 140,, 141, 142, and a contact 140, for energizing the electromagnet 163, which correspond to the contacts 39, 40, 40,, 41, 42 shown in FIG. 1 except for the electromagnet 163. When the casing is received in the player unit, these contacts are brought into contact with respective further contacts 39', 40', 40,, 40 41', 42'. The contact 40,, is not shown in FIG. 1, however, it is connected to the output terminal of the amplifier 76 (FIG. 4) so that it is not used in the radio cartridge as shown in FIG. 1.

Now the operation of the embodiment shown in FIG. 5 will be described hereinafter.

Depression of the pushbutton rod 182 causes the lever 127 to be counterclockwise swung against the bias of the spring 129 to abut the pinch roller 131 against the capstan 51 allowing the magnetic plate 162 to be attracted by the electromagnet 163. The lever 184 may be maintained in the position shown by the solid line of the drawing even if depression of the pushbutton 184 is released since the lever 127 is magnetically retained by the electromagnet 163. This allows the pinch roller 131 to be continuously rotated to thereby rotate the drum 134 with the operating shaft 136 for the tuning element 135.

When the tuning element tunes in the frequency of the radio wave, the pulse current is applied to the electromagnet 163, as in the manner of the embodiment of FIG. 1 to release the electromagnet 163 from magnetical attraction of the magnetic plate 162. At this point, the lever 127 is returned by the bias of the spring 129 to the position shown by the dotted line of the drawing Thus, the pinch roller 131 is moved away from the capstan 51 so that the tuning element 135 is maintained in the condition where it is set to the desired tuning position. In this manner, the radio cartridge in FIG. 5 may be automatically tuned as in the same manner of the embodiment in FIG. 1. According to the embodiment in FIG. 5, the cartridge is not required to have the electromagnetic plunger 64 and the microswitch 56. Further, the electromagnet 163 may be received in the casing to not only simplify the arrangement but also serve for practical use.

Another modified radio cartridge is shown in FIG. 6. Like parts are denoted by like numerals in FIG. 1. Mounted within the inside of the front wall 200, of a casing 220 are a high frequency input terminal, detection output terminal, AV C voltage output terminal, power source terminal which are all for a receiving station (not shown) stored in the casing 220. A connector 201 is also provided within the inside of the front wall 200, and includes a plurality of connecting pins to which switches are connected. The connector 201 is adapted to be electrically connected to a connector 202 which is mounted in the player unit when the radio cartridge is received in the player unit. Rotatably pivoted by a pillow block (not shown) to a bottom plate 200, of the casing 220 is a shaft 203 which pivotally carries a swingable lever 204. The lever 204 includes a pair of parallel plates 205, and 205, which are provided with apertures 206, and 206,, respectively. These apertures allow the shaft 203 to pass therethrough. Slits 207, and 207, are also bored through the plates 205, and 205,, respectively. Rod springs 208, and 208, of which one ends are secured to the plates extend beyond these slits. An extension 209 is integrally formed with the plate 205,. The extension 209 passes through an opening (not shown) formed in the front wall 200, and projects forwardly of the casing. A magnetic plate 210 is fixed to a flange portion projecting from the plate 205,. An electromagnet 211 is attached to the bottom plate 200, to be opposed to the magnetic plate 210. The magnetic plate 210 and the electromagnet 211 are similar to those shown in FIG. 1. A belt wheel 212 is fixed to the shaft 203 between the plates 205, and 205,. A pinch roller 214 is also attached to a shaft 213 which is loosely carried by the slots 207, and 207,. The shaft 213 is normally urged upwardly by the two rod springs 208, and 208, as shown in FIG. 6. A spring 216 extends between the lever 204 and a pin 215 fixed to the bottom plate 200, to urge the lever 204 counterclockwise. It will be understood that the rotating force of the lever 204 is arrested by a stop pin 217 attached to the bottom plate 200,. A pushbutton rod 218 is slidably supported by a guide 219 within the casing 200 and the one end of the rod 218 is opposed to the one end of the lever 204 at the plate 205, while the other passes through the opening (not shown) in a rear wall 200,. A pushbutton 220 is attached to the one end of the rod 218 projecting downwardly of the casing 200. A tuning element 221 is provided within the casing 200 and a drum 223 is attached to an operating shaft 222 for rotating the tuning element. A belt 224 extends round the shaft 213 and the belt wheel 212. The drum 223 is thus rotated by the belt 224, belt wheel 212, shaft 203, belt 225 when the capstan 214 is rotated. The drum 223 is similar to the drum 34 in the structure in FIG. 2. A microswitch 226 is fixed to the bottom plate 200, so as to allow the actuator to be positioned adjacent the lower plate 205,. The microswitch 226 is adapted to close its contact when the lever is in a normal position or to open it contact when the lever 204 is retained by the electromagnet 211. The microswitch 226 is also incorporated in a circuit for connecting the inspection output terminal for the receiving station (not shown) in the casing and the contact pin corresponding to the output terminal of the connector 201. Two switches 227 and 228 are provided within the player unit for the radio cartridge, the former having a function of the door switch 54 (FIG. 1) and the latter being operated by the lever extension 209.

The switch 228 in FIG. 8 comprises a movable contact 227 operated by the casing 200 being inserted into the player unit, and a fixed contact 227, opposite to the contact 227,. The switch 228 further comprises a movable contact 228, which is opposed to the fixed contact 227 and is operated by the lever extension 209 and a fixed contact 228, in opposite to the movable contact 228,. Connection between the movable contact 227, and the fixed contact 227, is broken off if the radio cartridge is not inserted into the player unit. At this point, the fixed contact 227, is brought into contact with the fixed contact 228,. When the radio cartridge is inserted into the player unit, the movable contact 227, is depressed by a portion of the 'front wall 200, and is caused to contact the fixed contact 227,

while the movable contact 228 is depressed by the extension 209 to break off connection with the fixed contact 227,. At this time, the movable contact 228, is not brought into contact with the fixed contact 228,. Contact 228 is depressed by the extension 209 and caused to contact the fixed contact 228 when the lever 204 is rotated for selecting the channel.

As shown in FIG. 8, the switches 227, 228 are incorporated in a current supply circuit for amplifier stations each provided in a capstan motor and the player unit. That is, a capstan motor 231 is connected through the switch 228 or the mova ble contact 228 and the switch 227 to the power source 230 while an amplifier station 232 is connected through the switch 227 to the power source 230. The switches 227, 228 in FIG. 8 are such that the lever 204 is retained by the electromagnet 211 when the radio cartridge is inserted into the player unit. That is, the movable contact 227 is brought into contact with the fixed contact 227, and the other movable contact 228, is caused to contact with the other fixed contact 228, so that the capstan motor 231 and the amplifier station 232 are energized by the current from the power source 230 and are actuated.

Again, referring to FIG. 6, the operation of the radio cartridge is as follows. When the radio cartridge is inserted into the player unit, the connector 201 and 202 are electrically connected to supply current as desired to the receiving station (not shown) for its actuation and the movable contact 227, and the fixed contact 227, are connected to each other to energize the amplifier station (FIG. 8). However, the movable contact 228 for the switch 228, is not brought into 204 is positioned to engage the stop pin 217 to keep the pinch roller 214 away from the capstan 51. This causes the capstan motor 231 (FIG. 8) not to be energized. When the pushbutton rod 218 with the button 220 is depressed, the lever 204 is counterclockwise-rotated to allow the magnetic plate 210 to attract the electromagnet 211 and to cause the movable contact 228 to contact the fixed contact 228,. The capstan motor 231 is then energized to rotate the capstan 51 and the pinch roller 214 abuts against the capstan 51, as shown in FIG. 6. As a result, rotation of the capstan 51 is imparted to the drum 223 rotating the shaft 222 for the tuning element 221.

Now, the tuning element 221 is tuned to the frequency of the radio broadcast wave, the pulse current is drained to the electromagnet 211, as in the same manner of the embodiment in FIG. 1, to disengage the electromagnet 211 from the magnetic attraction of the magnetic plate 210 so that the lever 204 is returned to its normal position by the bias of the spring 216. This allows the pinch roller 214 to move away from the capstan so that the tuning element 221 is maintained in the desired tuning position. In addition, the movable contact 228 and the fixed contact 228, for the switch 228 are disconnected from each other and the capstan motor 231 is deenergized to prevent rotation of the capstan 51. As mentioned above, the radio cartridge in FIG. 6 is capable of automatic tuning as in the cartridge in FIGS. 1 and 5. The radio cartridge illustrated in FIG. 6 provides the advantage that the current used is very small and good reception is obtained with less noise since the capstan motor 231 is only operated during automatic tuning and is not operated in receiving the radio broadcast wave. During automatic tuning in which the tuning element 221 is varied, the microswitch 226 is operated by the lever 204 to prevent the detection output signal for the receiving station from being applied to the amplifier station 232 so that noise cannot be generated from the speaker during nontuning. Further, abutment of the pinch roller 214 with the capstan 51 is sufficiently effected by the bias of the rod springs 208, and 208,.

Referring to FIG. 9, there is shown a casing of a type different from each of these as described heretofore. Like parts are also indicated by like numerals.

A bottom plate 301 is provided at the front edge thereof with an abutment 307 which is of slidable member and may be engaged by the capstan 51. The guide roller 48 is so positioned in the player unit that a depression 308 formed in a sidewall 306 does not fully receive the roller and thereby the roller 48 may engage the depression 308 at the open end thereof. With this arrangement, the force by the bracket 49 is resolved into a force urging the casing 300 leftwardly or upwardly. Accordingly, the abutment 307 may abut against the capstan 51 by the bias of the bracket 49. The abutment 307 is of slidable member not to interfere with rotation of the capstan 51 and is substantially coplanar with the bottom plate 301 but not positioned in the path of the pinch roller when engagement of the capstan is established. Two rotatable levers 31 1, 312 are coaxially mounted on a shaft 310 attached to the bottom plate 301. These levers 311, 312 are provided with respective sleeves 313, 314, as will be detailed in FIG. 11, by which the levers 311, 312 are supported. An upwardly projecting end 315 is formed on the lever 311 at one end thereof and an upwardly projecting portion 316 is formed on the other lever 312 on one side thereof so as to be opposed to the end 315. An adjusting screw 317 is mounted on the end 315 and extends to the portion 316. A spring 318 which is wound to the sleeve 314 is interposed between the sleeves 311 and 312 to be urged in the reverse directions in relation to each other. The bias of the spring 318 is arrested by abutment of the adjusting screw 317 with the portion 316. A pinch roller 320 is rotatably mounted on a shaft 319 attached to the lever 311 and a belt wheel 321 is fixed to a pinch roller 320. The lever 311 is provided at the other end thereof with an extension 311 which passes through an opening (not shown) formed in a slant wall 309 between the front wall 303 and the sidewall 306 and projects outwardly of the casing 300. A spring 322 extends between the lever 312 and a pin 323 on the bottom plate 301 to urge the lever 312 clockwise. Swingable movement of the lever 312 is prevented by abutting the lever 311 against a stop pin 324 projecting from the bottom plate 301. When the lever 311 abuts against the stop pin 324, the end of the extension 311, is positioned rearwardly of the plane defined by the front wall 303 but projects from such the plane by rotation of the lever 311 counterclockwise. Attached to the upwardly projecting flange portion of the lever 312 is a magnetic plate 325 to which an electromagnet 326 is opposed and fixed to the bottom plate 301. The electromagnet 326 includes three exciting coils 326,, 326,, 326 as shown in FIG. 10(a), which will be detailed hereinafter. The casing 300 stores a tuning element 327 and a drum 329 fixed to a tuning element operating shaft 328. The drum 329 is similar to the drum 34 in FIG. 2 and is provided with tuning dials on the surface and the periphery thereof. A portion of the drum 329 passes through an opening 304, in the rear wall 304 and projects outwardly of the casing 300 so as to be manually operated. A belt 330 extends round the drum 329 and the belt wheel 321 to reduce rotation of the pinch roller 320 and impart the same to the drum. Bored through the top plate 302 is an opening 331 (FIG. 12) adjacent which five contacts 333, 334, 335, 336, and 337 are arranged. These contacts are insulated by an insulating base 332 which is mounted within the casing 300. Each surface of these contacts is aligned with the plane of the top plate 302. The contact 333 serves as the high frequency signal input terminal for the receiving station (not shown) with the tuning element 327 (FIG. 9) within the casing 300. The contact 334 is the detection signal output terminal for the receiving station. The contact 335 is the positive voltage input terminal for the receiving station and for the exciting coil 326 (FIG. 10(a)) of the electromagnet 326 (FIG. 9). The contact 336 is the positive voltage input terminal for the exciting coil (FIG. 10(a)) of the electromagnet 326 (FIG. 9). And, the contact 327 is the negative voltage input terminal for the receiving station and each coil of the electromagnet 326. Further five contacts are also provided within the player unit to be brought into contact with the above-mentioned contacts when the radio cartridge is inserted into the player unit. Three contacts such as 335,, 336,, and 337, are opposed to the contacts 335, 336, and 337 are shown in FIG. 10(a).

Referring back to FIG. 9, a microswitch 338 is provided within the player unit so as to be opposed to the extension 311, of the lever 311. The microswitch 338 is adapted to close its contact by depression of an actuator 338, by the extension 311, when the lever 311 is rotated. The microswitch 338 with a manually operating switch 339 is incorporated in a circuit for energizing a capstan driving motor 340. That is, the closing of the microswitch 338 and the switch 339 will apply the current from a power supply 341 to the motor 340 for its actuation. An amplifier circuit 342 is connected by the switch 339 to the power supply 341 to amplify the detection output signal for the receiving station when using the radio cartridge or the output signal for the magnetic head 52 when using the endless magnetic tape cartridge.

The operation of the circuit for the electromagnet 326 is now described with reference to FIG. 10(a). Like parts are denoted by like numerals in FIGS. 9 and 12.

The exciting coil 326, is connected at the one end thereof through the contacts 336, 336, and a manually operating pushbutton switch 351 in the player unit to the plus pole of the power supply 350 while it is also connected at the other end thereof through the contacts 337, 337, to the minus pole of the source 350. The closing of the switch 351 allows the exciting coil 326, to receive the current from the power source 50 to thereby generate the high magnetic flux. Energization of the exciting coil 326, attracts the magnetic plate 325 (FIG. 9) to rotate thereover 312 against the bias of the spring 322. At this point, the lever 311 with the lever 312 is rotated to abut the pinch roller 309 against the capstan 51. The exciting coil 326 is connected at the one end thereof through a resistor 352, and the contacts 335, 335, to the plus pole of the source 350 while it is connected at the other end thereof through the contacts 337, 337, to the minus pole of the source 350. Therefore, the weak current controlled by the resistor 352 is normally applied to the exciting coil 326,. The magnetic flux generated in the exciting coil 326, is not enough to attract the lever 312 against the bias of the spring 322 as is the flux generated in the coil 326, but is enough to prevent the once attracted lever 312 by the coil 326, from returning to its original position by the spring 322 after the coil 326, is deenergized. The exciting coil 326;, is connected at the one end thereof to the AVC voltage output terminal for the receiving station while it is connected at the other end thereof through the contacts 337, 337, to the minus pole of the source 350 so that the current in response to the AVC voltage is applied to the coil 326 The drift of the magnetic flux generated in the coil 326;, is such that it erases the magnetic flux generated in the coil 326, and the magnetic force decays when the AVC voltage reaches the extreme value in tuning of the receiving station to thereby return the lever 312 to its original position by the bias of the spring 322. The pushbutton switch 351 is used for selecting the recording track or the channel in the use of the endless magnetic tape cartridge and serves to control energization the electromagnetic plunger 353 for vertically moving the magnetic head. Numerals 354, 355 are the power source input terminals. As mentioned, in this instance the electromagnet 326 includes the three exciting coils.

FIG. 10(b) shows a circuit in which an electromagnet having two exciting coils is used. Like parts are designated by like numerals with primes in FIG. 10(a). The electromagnet 326' includes two exciting coils 326,, 327; which are similar to the coils 326,, 326,, but has no coil corresponding to the coil 326, in FIG. 10(a). A pushbutton switch 360 is provided in parallel to a resistor 352' incorporated in a circuit for energizing the coil 326,. The closing of the switch 360 applies the strong current to the coil 326, to attract the lever 312 (FIG. 9) against the bias of the spring 322. The opening of the switch 360 normally applies the weak current controlled by the resistor 352' to the coil 326, and mode of operation of the coil 326,, is the same as that of the coil 326,. Similarly, the coil 326, is the same as the coil 326,. In this instance, the coil 326, functions as the coils 326,, 326, in FIG. 10(0).

Mode of operation of the radio cartridge in FIG. 9 is as follows.

Depression of the pushbutton switch (FIG. 10(a)) allows the electromagnet 326 to attract the magnetic plate 325 to thereby rotate the rotatable lever 312 with the lever 311. With rotation of the lever 311, the extension 31 l, depresses the actuator 338 to close the contact of the microswitch 338 so that the capstan motor 340 is actuated, and if the switch 339 is closed, the capstan 51 is rotated while the pinch roller 320 abuts against the capstan 51 to rotate the pinch roller 320 and the drum 329. Even after releasing depression of the pushbutton switch 351, the magnetic plate 325 is maintained attractive to the electromagnet 326 by the magnetic flux generated in the exciting coil 326 FIG. 10(a)). Accordingly, the capstan motor 340 keeps on its rotation so that abutment of the pinch roller 320 with the capstan 51 is maintained to rotate the drum 329. This rotation of the drum 329 varies the tuning element 327 and until the receiving frequency at the receiving station corresponds to the frequency of the radio wave at which time the magnetic flux generated in the coil 326, (FIG. 10(a)) is erased by the current drained to the coil 326 (FIG. 10(a)) to release the electromagnet 326 from attraction of the magnetic plate 325 so that the levers 311, 312 are returned to their original position by the bias of the spring 322. As a result, the contact of the microswitch 338 is opened to deenergize the capstan motor 340 to terminate rotation of the capstan 51 to thus keep the pinch roller 320 away from the capstan 51 terminating rotation of the drum 329. Consequently, the tuning element 327 is set to the point to tune in the frequency of the arrival electric wave. It is apparent that SN ratio of the receiving station is improved since the capstan motor 340 is no longer actuated after automatic tuning is completed. In automatic tuning, abutment of the capstan 51 with the pinch roller 320 is effected by the bias of the spring 318 (FIG. 11) interposed between the levers 311 and 312 so that relative position of the lever 312 and the electromagnet 326 is roughly controlled.

In order to product a slight gap between the magnetic circuit open end of the electromagnet 326 and the magnetic plate 325 when the electromagnet attracts the magnetic plate, the angle formed the levers 311 and 312 is adjusted by turning the screw 322. In this manner, the period of time in which the levers 31 1 and 312 are returned to its original position, may be reduced when the current for erasing the magnetic flux generated in the coil 326 is applied to the coil 326,, With this arrangement, the tuning element 329 is accurately set to the tuning position of the radio wave. The slight gap between the magnetic circuit open end of the electromagnet and the magnetic plate is formed by allowing the abutment 307 to abut against the capstan 51 to constantly hold a distance between the capstan 51 and the pinch roller 320. In order to constantly hold the distance between the capstan and the pinch roller, a stop pin (not shown) against which the front wall 303 abuts may be fixed to the player unit deck. In FIG. (a), the magnetic flux generated in the coil 326 is erased by the current applied to the coil 326,, however, the exciting coil 326 may be omitted and a switching transistor 356 may be provided as shown by the dotted line in series to the coil 326 to apply the AVC voltage of the receiving station to the base pole of the switching transistor 356 to thus control energization of the coil 326 by action of the switching transistor 356. Although the magnetic plate 325 is fixed to the lever 312 according to the embodiment in FIG. 9, such THE MAGNETIC plate 325 may be omitted if the lever 312 is made of mill steel.

The detection output signal may be taken out by the magnetic head provided within the casing but not the contact, that is, the variation of the magnetic flux generated in the magnetic head is picked up by the magnetic head in the player unit. This is the case with the use of the radio cartridge or the endless magnetic tape cartridge.

The invention and its attendant advantages will be understood from the foregoing description. It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A radio cartridge for reception and playing of radio broadcasts through the audio output stage of a magnetic tape cartridge player unit, said player unit having a tape driving device including a capstan and an electrical motor for driving the capstan, and a tape recording and reproducing circuit, comprising a casing having the same dimensions as the magnetic tape cartridge, said casing having a front wall with an opening therein, a radio receiving circuit in said casing, said radio receiving circuit having a tuning element provided with an operating shaft, lever means mounted for pivotal movement in said casing, a rotatable pinch roller mounted on said lever means, said lever means being positioned in said casing such that a portion of said pinch roller passes through said opening, said pinch roller being adapted to be positioned adjacent said capstan when the radio cartridge is in the player unit, first maintaining means for maintaining said lever means in a first position where said pinch roller is remote from said capstan when the radio cartridge is in the player unit, operating means for moving said lever means from said first position to a second position where said pinch roller is engaged with and rotated by said capstan when said radio cartridge is in the player unit, second maintaining means for maintaining said lever means in said second position, means for imparting the rotation of said pinch roller to said operating shaft, a sensing circuit for producing an electrical signal in response to sensing that said radio receiving circuit is tuned to a broadcasting radio wave, means for applying said electrical signal to said second maintaining means, said second maintaining means being adapted to release said lever means in response to said electrical signal, means for moving said lever means from the second position to the first position when said second maintaining means is released, and a group of contacts mounted on said casing for applying electrical current to said radio receiving circuit and for generating the output signal of the circuit,

each contact of said group of contacts being adapted to be brought into electrical contact with a corresponding group of contacts on said player unit when said radio cartridge is in said player unit.

2. A radio cartridge for reception and playing of radio broadcasts through the audio output stage of a magnetic tape cartridge player unit, said player unit having a tape driving device including a capstan and an electrical motor for driving the capstan, and a tape recording and reproducing circuit, comprising a casing having the same dimensions as the magnetic tape cartridge, said casing having a front wall with an opening therein, a radio receiving circuit in said casing, said radio receiving circuit having a tuning element provided with an operating shaft, lever means mounted for pivotal movement in said casing, a rotatable pinch roller mounted on said lever means, said lever means being positioned in said casing such that a portion of said pinch roller passes through said opening, said pinch roller being adapted to be positioned adjacent said capstan when the radio cartridge is in the player unit, spring means biasing said lever means to a first position where said pinch roller is remote from said capstan when the radio cartridge is in the player unit, operating means for moving said lever means against the bias of said spring means from said first position to a second position where said pinch roller is engaged with and rotated by said capstan when said radio cartridge is in the player unit, an electromagnet for magnetically attracting said lever means and for maintaining said lever means in said second position by magnetic force, means for imparting the rotation of said pinch roller to said operating shaft, a sensing circuit for producing an electrical signal in response to sensing that said radio receiving circuit is tuned to a broadcasting radio wave, means for applying said electrical signal to said electromagnet, said electromagnet being adapted to release said lever means in response to said electrical signal whereby said lever means is returned to the first position at the same time that rotation of said operating shaft of said tuning element is interrupted and said tuning element is automatically set to the receiving position for the broadcasting wave, and a group of contacts mounted on said casing for applying electrical current to said radio receiving circuit and for generating the output signal of the circuit, each contact of said group of contacts being adapted to be brought into electrical contact with a corresponding group of contacts on said player unit when said radio cartridge is in said player unit.

3. A radio cartridge as set forth in claim 2 wherein a drum is mounted on said operating shaft for rotation with said shaft, said drum being provided with a tuning dial at the periphery thereof, and a portion of said drum passes through an opening formed in the rear wall of said casing and outwardly extends beyond said casing.

4. A radio cartridge as set forth in claim 3 wherein said lever means including an extension extending beyond said casing, said extension having adapted to operate a switch in the player unit for actuating said motor when said lever means is swung from said first to said second position.

5. A radio cartridge as set forth in claim 3 wherein said actuating means is a rod slidably mounted within said casing, one end of said rod being adjacent to said lever means, the other end projecting from the casing through a hole formed in said rear wall of the casing, said other end being provided with a pushbutton, said rod being positioned such that manual depression of the pushbutton moves said lever means to said second position.

6. A radio cartridge as set forth in claim 5 wherein said means imparting rotation of said pinch roller to said operating shaft of said tuning element is a belt which extends round said axis of the pinch roller and said drum.

7. A radio cartridge as set forth in claim 5 wherein said electromagnet includes a normally energized first exciting coil and a second exciting coil adapted to be excited by said electric signal, said coils being arranged such that the magnetic flux generated in said second exciting coil erases the magnetic flux generated in said first exciting coil to release retention of said lever means by said electromagnet.

8. A radio cartridge as set forth in claim 3 wherein said electromagnet includes a plurality of exciting coils, and said operating means is an exciting coil adapted to generate a magnetic flux sufficient to swing said lever means from said first to said second position.

9. A radio cartridge as set forth in claim 8 wherein said cas- 

1. A radio cartridge for reception and playing of radio broadcasts through the audio output stage of a magnetic tape cartridge player unit, said player unit having a tape driving device including a capstan and an electrical motor for driving the capstan, and a tape recording and reproducing circuit, comprising a casing having the same dimensions as the magnetic tape cartridge, said casing having a front wall with an opening therein, a radio receiving circuit in said casing, said radio receiving circuit having a tuning element provided with an operating shaft, lever means mounted for pivotal movement in said casing, a rotatable pinch roller mounted on said lever means, said lever means being positioned in said casing such that a portion of said pinch roller passes through said opening, said pinch roller being adapted to be positioned adjacent said capstan when the radio cartridge is in the player unit, first maintaining means for maintaining said lever means in a first position where said pinch roller is remote from said capstan when the radio cartridge is in the player unit, operating means for moving said lever means from said first position to a second position where said pinch roller is engaged with and rotated by said capstan when said radio cartridge is in the player unit, second maintaining means for maintaining said lever means in said second position, means for imparting the rotation of said pinch roller to said operating shaft, a sensing circuit for producing an electrical signal in response to sensing that said radio receiving circuit is tuned to a broadcasting radio wave, means for applying said electrical signal to said second maintaining means, said second maintaining means being adapted to release said lever means in response to said electrical signal, means for moving said lever means from the second position to the first position when said second maintaining means is released, and a group of contacts mounted on said casing for applying electrical current to said radio receiving circuit and for generating the output signal of the circuit, each contact of said group of contacts being adapted to be brought into electrical contact with a corresponding group of contacts on said player unit when said radio cartridge is in said player unit.
 2. A radio cartridge for reception and playing of radio broadcasts through the audio output stage of a magnetic tape cartridge player unit, said player unit having a tape driving device including a capstan and an electrical motor for driving the capstan, and a tape recording and reproducing circuit, comprising a casing having the same dimensions as the magnetic tape cartridge, said casing having a front wall with an opening therein, a radio receiving circuit in said casing, said radio receiving circuit having a tuning element provided with an operating shaft, lever means mounted for pivotal movement in said casing, a rotatable pinch roller mounted on said lever means, said lever means being positioned in said casing such that a portion of said pinch roller passes through said opening, said pinch roller being adapted to be positioned adjacent said capstan when the radio cartridge is in the player unit, spring means biasing said lever means to a first position where said pinch roller is remote from said capstan when the radio cartridge is in the player unit, operating means for moving said lever means against the bias of said spring means from said first position to a second position where said pinch roller is engaged with and rotated by said capstan when said radio cartridge is in the player unit, an electromagnet for magnetically atTracting said lever means and for maintaining said lever means in said second position by magnetic force, means for imparting the rotation of said pinch roller to said operating shaft, a sensing circuit for producing an electrical signal in response to sensing that said radio receiving circuit is tuned to a broadcasting radio wave, means for applying said electrical signal to said electromagnet, said electromagnet being adapted to release said lever means in response to said electrical signal whereby said lever means is returned to the first position at the same time that rotation of said operating shaft of said tuning element is interrupted and said tuning element is automatically set to the receiving position for the broadcasting wave, and a group of contacts mounted on said casing for applying electrical current to said radio receiving circuit and for generating the output signal of the circuit, each contact of said group of contacts being adapted to be brought into electrical contact with a corresponding group of contacts on said player unit when said radio cartridge is in said player unit.
 3. A radio cartridge as set forth in claim 2 wherein a drum is mounted on said operating shaft for rotation with said shaft, said drum being provided with a tuning dial at the periphery thereof, and a portion of said drum passes through an opening formed in the rear wall of said casing and outwardly extends beyond said casing.
 4. A radio cartridge as set forth in claim 3 wherein said lever means including an extension extending beyond said casing, said extension having adapted to operate a switch in the player unit for actuating said motor when said lever means is swung from said first to said second position.
 5. A radio cartridge as set forth in claim 3 wherein said actuating means is a rod slidably mounted within said casing, one end of said rod being adjacent to said lever means, the other end projecting from the casing through a hole formed in said rear wall of the casing, said other end being provided with a pushbutton, said rod being positioned such that manual depression of the pushbutton moves said lever means to said second position.
 6. A radio cartridge as set forth in claim 5 wherein said means imparting rotation of said pinch roller to said operating shaft of said tuning element is a belt which extends round said axis of the pinch roller and said drum.
 7. A radio cartridge as set forth in claim 5 wherein said electromagnet includes a normally energized first exciting coil and a second exciting coil adapted to be excited by said electric signal, said coils being arranged such that the magnetic flux generated in said second exciting coil erases the magnetic flux generated in said first exciting coil to release retention of said lever means by said electromagnet.
 8. A radio cartridge as set forth in claim 3 wherein said electromagnet includes a plurality of exciting coils, and said operating means is an exciting coil adapted to generate a magnetic flux sufficient to swing said lever means from said first to said second position.
 9. A radio cartridge as set forth in claim 8 wherein said casing is provided with an abutment, said abutment being adapted to abut against said capstan when the radio cartridge is in the player unit to accurately maintain the relative position of said pinch roller and the capstan when said lever means is in said first position. 